Commit 1271a7b9 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Thierry Reding
Browse files

pwm: Zero-initialize the pwm_state passed to driver's .get_state() 



This is just to ensure that .usage_power is properly initialized and
doesn't contain random stack data. The other members of struct pwm_state
should get a value assigned in a successful call to .get_state(). So in
the absence of bugs in driver implementations, this is only a safe-guard
and no fix.

Reported-by: default avatarMunehisa Kamata <kamatam@amazon.com>
Link: https://lore.kernel.org/r/20230310214004.2619480-1-u.kleine-koenig@pengutronix.de


Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 8caa81eb

drivers/pwm/core.c

+10 −2
Original line number Diff line number Diff line
@@ -115,7 +115,14 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) 
	}



	if (pwm->chip->ops->get_state) {

		struct pwm_state state;

		/*

		 * Zero-initialize state because most drivers are unaware of

		 * .usage_power. The other members of state are supposed to be

		 * set by lowlevel drivers. We still initialize the whole

		 * structure for simplicity even though this might paper over

		 * faulty implementations of .get_state().

		 */

		struct pwm_state state = { 0, };



		err = pwm->chip->ops->get_state(pwm->chip, pwm, &state);

		trace_pwm_get(pwm, &state, err);
@@ -448,7 +455,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm, 
{

	struct pwm_state *last = &pwm->last;

	struct pwm_chip *chip = pwm->chip;

	struct pwm_state s1, s2;

	struct pwm_state s1 = { 0 }, s2 = { 0 };

	int err;



	if (!IS_ENABLED(CONFIG_PWM_DEBUG))
@@ -530,6 +537,7 @@ static void pwm_apply_state_debug(struct pwm_device *pwm, 
		return;

	}



	*last = (struct pwm_state){ 0 };

	err = chip->ops->get_state(chip, pwm, last);

	trace_pwm_get(pwm, last, err);

	if (err)